When a refrigerant cycle is driven, it is required to satisfy standards by reducing generated noise, in particular, electrical noise. For instance, in Japan, the standards are described in the provision in Section 2 of the ministerial ordinance of Electrical Appliances and Material Safety Law, more specifically, there are so-called IEC-J standards J55001 (Standard for Noise Intensity), J55014-1 (Electromagnetic Compatibility-Requirement for Household Appliances, Electric Tools and Similar Apparatus), and J55022 (Information from Technology Equipment-Radio Disturbance Characteristics-Limits and Methods of Measurement). In Europe, there are EN55014-1 (Electromagnetic Compatibility.—Requirements for Household Appliances, electric tools and similar apparatus. Emission) and EN55022 (Information Technology Equipment.—Radio Disturbance Characteristics.—Limits and methods of measurement). Those standards do not need to be satisfied all the time, and it is sufficient only to reduce electrical noise under conditions set in advance. That is, the refrigerant cycle is required to perform an operation for satisfying the standards in a case where the standards need to be satisfied, and perform another operation in a case where the standards do not need to be satisfied.
In order to reduce the generation of electrical noise, it is conceivable to, for example, change a structure of an expansion valve.
Note that Patent Document 1 describes a technique of changing a structure of an expansion valve to reduce cavitation noise.
Patent Document 1: Japanese Patent Application Laid-Open No. 09-133434